Means for applying a liquid abrasive over the surface of a rotatable lapping table of a lapping machine

ABSTRACT

Means for applying a liquid abrasive over the surface of a rotatable lapping table of a lapping machine comprising delivering the abrasive to a well or cup in the center of the table, allowing the abrasive to fill the well to a point of overflowing therefrom and then spreading the abrasive over the surface of the lapping table by capillary action created by rotation of a wear or work ring on the table with the peripheral portion overlapping the edge of the well in the path of overflowing abrasive from the well.

United States Patent Day [541 MEANS FOR APPLYING A LIQUID ABRASIVE OVER THE SURFACE OF A ROTATABLE LAPPING TABLE OF A LAPPING MACHINE [72] Inventor: Lawrence Day, Chicago, Ill. I [73] Assignee: Spitfire Tool & Machine Co., Inc.,

Chicago, Ill.

[22] Filed: Sept. 24, 1970 [21] Appl. No.: 75,046

[52] US. Cl. ..51/131, 51/263 [51] Int. Cl. ..B24b 37/09 [58] Fieldof Search ..Sl/l29, 131, 317, 292, 263

[56] References Cited UNITED STATES PATENTS 3,375,614 4/1965 Boettcher ..51/129 [151 3,683,562 [4s] Aug. 15, 1972 905,486 12/1908 Woodruff ..51/131 3,128,580 4/1964 Davis ..51/131 3,388,506 6/1968 Boettcher ..51/129 Primary Examiner-Harold D. Whitehead Attorney-Edward C. Threedy [5 7] ABSTRACT Means for applying a liquid abrasive over the surface of a rotatable lapping table of a lapping machine comprising delivering the abrasive to a well or cup in the center of the table, allowing the abrasive to fill the well to a point of overflowing therefrom and then spreading the abrasive over the surface of the lapping table by capillary action created by rotation of a wear or work ring on the table with the peripheral portion overlapping the edge of the well in the path of overflowing abrasive from the well.

6 Claims, 5 Drawing Figures Patented Aug. 15, 1972 3,683,562

2 Sheets-Sheet l VENTOR. If. 06 Z/A s/vcz 941 SUMMARY OF THE INVENTION I-Ieretofore in the application of supplying a liquid abrasive to the lapping surface (i.e., work surface) of a fiat lapping table of a lapping machine, it was customary to deliver the liquid abrasive to a predetermined point above the working area of such surface and then allowing the liquid abrasive to flow upon such surface where it is encountered by the rotatable workholder or wear rings and spread over the work surface, this being accomplished successively by each ring as it'comes into contact with the liquid abrasive.

My invention has for its principal object a simple and expeditious arrangement for delivering the liquid abrasive at a point centrally located with respect to the lapping table and from which point each wear ring or workholder independently contacts the abrasive and by capillary action spreads a uniform film of liquid abrasive over the entire surface of the lapping table without any overflow or excessive application of the liquid abrasive.

This and other salient objects of the invention are accomplished by the preferred form of construction shown in the accompanying drawings, in which:

FIG. 1 is a fragmentary perspective view of a lapping machine having my invention incorporated therein;

FIG. 2 is a top plan view of the same;

I FIG. 3 is a fragmentary top plan view similar to FIG. 2 schematically illustrating the contact of the workholder or wear ring with the abrasive for spreading the abrasive over the surface of the lapping table by capillary action;

FIG. 4 is a sectional detail view taken substantially on line 4-4 of FIG. 3 and showing the abrasive cup removed from the table;

FIG. 5 is a vertical sectional detail view taken on line 5-5 of FIG. 4.

The conventional lapping machine such as shown in United States Letters Patent No. 3,032,937 dated May 8, 1962, includes a base having a top wall 11 within which is rotatably mounted a circular lapping table 12. Mounted upon the lapping table 12 are one or more workholders or wear rings 13 which are radially positioned upon the table 12. A pressure plate 14 is positioned in the ring 13 upon the work being lapped. So that the work may be placed in or removed from the ring 13, the pressure plate 14 is supported for vertical adjustment by a unit 15 preferably constructed and operated in accordance with the aforesaid patent. The lapping machine further includes a liquid abrasive dispenser generally indicated at 16, such as shown and described in US. Pat. No. 3,261,510 dated July 19,

1966, serving to recirculate the liquid abrasive from and to the working surface of the table 12 through the medium of a centrifugal pump or the like. This abrasive dispenser includes a delivery trough 17 preferably triangular in cross section and tapering to a point indicated at 18. a

My improvement in such lapping machine includes the forming centrally in the lapping table 12 of a socket 19. In the socket 19 I position a removable cup 20 which, when mounted in the socket 19, provides a well which receives the liquid abrasive from the trough 17.

To facilitate positioning and removing .the cup 20 in the socket 19, I provide a finger bolt 21 which may be conveniently grasped by the fingers of the hand for the purpose of removing and replacing the cup 20 in the socket 19. The bolt 21 is threaded into an opening 22 formed in the bottom wall 23 of the cup 20. This bottom wall 23 is frusto-conical in cross section as shown in FIG. 5, so as to direct the liquid abrasive from the center of the cup 20 toward the side walls 24 thereof.

In FIG. 3 l have schematically illustrated the manner in which the abrasive is taken from the well by the rotating ring 13. The ring 13 being positioned on the surface of the lapping table 12, is held against rotation therewith but is free to rotate about its axis by virtue of the rotatable motion of the lapping table. It is important to note, as shown in the drawings, that the wear ring 13 is so located upon the lapping table 12 that an edge portion of such ring will slightly overlie the peripheral edge of the cup 20 as indicated at 14 in FIGS. 1, 2 and 3. The transfer of the liquid abrasive onto the working surface of the lapping table 12 is at a rate such as to maintain at a constant and adequate level the liquid abrasive within the cup 20 for spreading by the ring to achieve a uniform film, thus avoiding excessive application of the liquid abrasive to the working surface of the lapping table 12.

As the ring 13 is thus rotated and as the liquid abrasive seeksto overflow from the well or cup 20, the ring 13 at the overlying point indicated at 14', will interrupt the overflowing abrasive, and the liquid abrasive by capillary action created by the rotation of the ring 13 on the lapping table 12, will be evenly spread in a uniform film over the entire working area covered by the ring 13 with respect to the surface of the lapping table 12.

As shown in FIG. 3, the trough 17 at its lower end portion is curved from longitudinal relation with the long axis of the trough. By this arrangement, the discharge end of the trough is located as near as possible to the center of the lapping table and between the adjacent rings 13. It will be particularly noted that each ring 13 functions to spread a film of liquid abrasive over the working area of the lapping plate 12 and over the area upon which the ring 13 operates.

After the lapping operation has been completed, the liquid abrasive may be easily removed and the well of the lapping plate cleaned by the simple removal of the cup 20 from the socket 19.

By the arrangement described above, the film of liquid abrasive will be uniformly and consistently spread and maintained over the working surface of the lapping table. This is highly desirable and important to assure precision lapping.

While I have illustrated and described the preferred form of construction for carrying my invention into effect, this is capable of variation and modification without departing from the spirit of the invention. I, therefore, do not wish to be limited to the precise details of construction set forth, but desire to avail myself of such variations and modifications as come within the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to protect by Letters Patent is:

1. An improvement in a lapping machine which commounted on said lapping table and rotatable thereby, and a liquid abrasive dispenser, the improvement comprising a. a centrally located well formed in the lapping table to receive liquid abrasive from the dispenser and from which well said abrasive overflows,

b. said rings located upon said lapping plate with an edge portion thereof overlying the peripheral edge of the well to interrupt overflowing liquid abrasive from the well and by capillary action spread a uniform film of liquid abrasive over the working surface of the lapping table,

c. said well comprising a socket formed in the lapping table and a removable cup mounted in said socket and into which the liquid abrasive is received from the dispenser.

2. The improvement defined in claim 1 wherein the dispenser includes an inclined trough for delivering the liquid abrasive to the well.

3. The improvement defined in claim 1 wherein the cup provides a frusto-conically shaped bottom wall.

4. The improvement defined in claim 1 wherein the cup provides a frusto-conically shaped bottom wall.

5. The improvement defined in claim 1 wherein the cup has a fingerpiece to facilitate removal of the cup from the socket.

6. The improvement defined in claim 3 wherein the cup has a fingerpiece to facilitate removal of the cup from the socket. 

1. An improvement in a lapping machine which comprises a rotatable lapping table, workholder rings mounted on said lapping table and rotatable thereby, and a liquid abrasive dispenser, the improvement comprising a. a centrally located well formed in the lapping table to receive liquid abrasive from the dispenser and from which well said abrasive overflows, b. said rings located upon said lapping plate with an edge portion thereof oVerlying the peripheral edge of the well to interrupt overflowing liquid abrasive from the well and by capillary action spread a uniform film of liquid abrasive over the working surface of the lapping table, c. said well comprising a socket formed in the lapping table and a removable cup mounted in said socket and into which the liquid abrasive is received from the dispenser.
 2. The improvement defined in claim 1 wherein the dispenser includes an inclined trough for delivering the liquid abrasive to the well.
 3. The improvement defined in claim 1 wherein the cup provides a frusto-conically shaped bottom wall.
 4. The improvement defined in claim 1 wherein the cup provides a frusto-conically shaped bottom wall.
 5. The improvement defined in claim 1 wherein the cup has a fingerpiece to facilitate removal of the cup from the socket.
 6. The improvement defined in claim 3 wherein the cup has a fingerpiece to facilitate removal of the cup from the socket. 